Gas-tight material webs, which are suitable especially for manufacturing gas-tight safety suits or chemical safety suits, are manufactured by fabricating coated fabrics, which are cut and sewn as in the clothing industry. The seams inevitably formed in the manufacturing process must be reclosed gas-tightly. Since safety suit materials that do not permit direct closing due to their structure have hitherto been used, the seams must be closed in an additional operation by applying a separate tape. These tapes were applied by bonding in the past, but a process called welding was alternatively developed recently, in which a thermoplastic polymer is brought to the seam location by two rollers by means of hot air and pressure and connected to the surface of the suit by vulcanization.
Since both the inside and the outside of the seams must be welded in this manner up to now, this process is very complicated and therefore accounts for a large portion of the manufacturing costs. For example, about 80 running meters of welding tape must be processed per suit. The requirements imposed on the materials for gas-tight chemical safety suits or other products, which use these materials, are varied and high. Thus, a large number of chemical resistances and gas permeation resistances must be demonstrated. The mechanical strengths against, for example, abrasion also imposed high requirements on the material used.
To meet these various requirements, various solutions were proposed for the material structure in the form of a multilayer material web, in which one layer, which forms the outside, usually consists of a flameproof and flame-retardant or flame-resistant material. Besides an elastomer layer, a film is processed, which represents the chemical barrier layer proper. An additional elastomer layer, which is the layer that makes possible the welding process described in the first place, is used on the inside of the chemical safety suit. The incorporated fabric layer increases the tear and puncture resistance of the multilayer material.
A laminate for chemical safety suits consisting of a two-sided film made of polyvinyl fluoride (PVF) on a layer consisting of chlorinated polyethylene (CPE) is disclosed in U.S. Pat. No. 4,675,228.
A prior-art multilayer material web appears, for example, from EP 0 668 823 B1, where a plurality of rubber layers are combined. The manufacturing costs of these prior-art material webs according to EP 0 668 823 B1 are high for the following reasons: The elastomers are applied to the fabric-film composite prepared in advance by a coating process or calendering. To reach the layer thicknesses of the elastomer that are necessary for sufficient resistance, these elastomers must be manufactured by a plurality of coating or calendering operations, i.e., the roll web must be led through the corresponding plant several times.